Let's try another approach then. When you start JBoss through run.bat (or run.sh) pass the -verbose:class JVM parameter. Like this(for run.bat): set JAVA_OPTS=%JAVA_OPTS% -Xms128m -Xmx512m -XX:MaxPermSize=256m -verbose:class | Then start JBoss. This will print out to STDOUT the classes being loaded and also the jar files being used for loading these classes. I would recommend redirecting the STDOUT output to some file, as the logs will be too huge: run.bat > classes_out.log Access your application to get the ClassCastException. The classes_out.log will contain the appropriate information about which jar is being used for loading the Changelist* classes (just do a text search in that log file for this class). View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4129094#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...